This invention relates to reinforcement hangers for automobile exhaust systems. More specifically, it relates to a woven fabric reinforcement that provides added support to such hangers at a relatively low cost.
It is a known practice in the suspension of automotive exhaust systems to support the exhaust pipe and/or tailpipe (exhaust conduits) at various points along the system length to fixed parts of a vehicle frame or chassis. Such support includes a pipe holding means. Conventional supporting hangers include, for example, a metal bracket attached to the underbody frame of the vehicle, a second bracket attached to the tailpipe, and a piece of flexible or resilient material connected between the ends of the brackets. In the conventional design, the resilient material is placed under tension by the weight of the exhaust system suspended therefrom.
A common difficulty with conventional hangers is that the resilient element tends to fatigue or otherwise to become progressively weak to the point where the resilient element fails, allowing the exhaust system components to fall down and create a dangerous situation, which is also costly to repair.
An additional problem with conventional hangers is that the arrangement cannot adequately compensate for conditions encountered under service conditions. Exhaust systems tend to elongate when they become hot and the exhaust system may be subjected to considerable shocks and other forces. There is no provision in conventional systems to accommodate sufficiency for axial thermal expansion and contraction of the metal pipe, and the resilient member does not adequately restrain lateral movements.
Currently, molded rubber hangers use welded steel bands or continuous spiral wrapped yarn bands to reinforce the hanger so as to increase the usable lifetime of the hanger. However, problems exist with these materials. Metal bands fail early due to metal fatigue from cyclic loading. Hangers reinforced with wrapped yam reinforcement are sturdier and perform better. However, it is costly and complex to manufacture hangers wrapped in yarn.
It is the primary purpose of this invention to provide an improved mounting or support system for exhaust systems used in automobiles that is more durable than prior art systems and is also relatively inexpensive to manufacture.
This object is accomplished by a molded rubber hanger having a fibrous reinforcing belt with a structure that provides enhanced bonding between the reinforcement and the predominant material of the hanger. The reinforcing material of the belt can be a continuously wound thread, or a fabric.
Typically, the predominant material of the hanger is rubber, and the reinforcing material of the belt is derived from polyester or nylon fiber. In the formation of the hanger, the belt is placed in a mold, into which molten rubber is then injected. Perforations are present at intervals around the belt; when molten rubber is injected into the mold, it can flow through the perforations to provide a secure mechanical bond between the belt and the rubber of the finished article.
The fabric consists of warp and weft threads. When the fabric is stressed, only the warp threads bear a significant load, and a minimal number of weft threads is required to hold the warp yarns in alignment. The weft threads also prevent individual warp threads from cutting through the rubber. The strength of the woven product is a result of the warp yarns. The warp threads may be positioned to allow for the perforations, down the center or the sides of the fabric. If a dense fabric is woven without a perforation, holes may be cut, punched, or melted through the center or elsewhere, at various intervals. The mechanical bonds at the perforations allow a multiwrap reinforcement to reach the maximum tensile strength of the yarn by preventing the wraps of fabric from slipping past each other.